Hot melt fragmentation extruder and process

ABSTRACT

A co-rotating twin screw extruder for forming fragments is disclosed. The extruder comprises of an intake zone for receiving one or more excipient(s) suitable for oral dosage or one or more excipient(s) suitable for oral dosage along with one or more active pharmaceutical ingredient, a melt zone for softening at least one excipient to form a viscous mass or melt and a fragmenting zone for fragmenting and cooling the viscous mass into cooled fragments and an extruder outlet for recovering the cooled fragments from the extruder.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Stage of International Application No.PCT/IN2014/000358, filed May 27, 2014, which was published in Englishunder PCT Article 21(2), which in turn claims the benefit of IndiaPatent Application No. 2295/CHE/2013, filed May 27, 2013. Bothapplications are hereby incorporated by reference herein.

BACKGROUND

Hot-melt extrusion (HME) is a widely applied technique in the plasticsindustry and has been demonstrated to be a viable method to prepareseveral dosage forms of pharmaceutical compositions. Hot-melt extrudeddosage forms are typically mixtures of active medicaments, functionalexcipients, and processing aids. HME also offers several functionaladvantages over traditional pharmaceutical processing techniques such aswet, dry and melt granulation. Such advantages include absence ofsolvents, few processing steps, continuous operation, the possibility ofthe formation of solid dispersions/solid solutions and improvedbioavailability. HME process can be carried out in a single screwextruder or a twin-screw extruder. Due to the self-cleaning advantageand configurable mixing capability of the co-rotating twin-screwextruder, the co-rotating twin-screw is increasingly preferred as thedevice for carrying out the HME process. Conventional HME processinvolves embedding a drug in a carrier under controlled conditions suchas temperature, residence time, mixing energy input, feed rate andpressure and forcing it through an orificed die or an open die tocollect the hot viscous mass or melt in the form of a strand, film or alump. A conventional extruder for HME process includes an intake zonethrough which the mixture of active ingredients and suitable excipientsare introduced, a melt zone for forming a viscous mass or melt and aconveying zone for conveying the hot viscous mass or melt out of theextruder. The barrel in the extruder is divided into differenttemperature zones that are set to specific temperatures as per the needof the extrusion process. Typically, the temperature of the viscousmass/melt along the length of the barrel is maintained such that thereis no solidification inside the extruder. (For example, Vasanthavada etal., 2010 suggest the cooler zone is towards the feeder and the warmerzone towards the exit). Heat for fusion is supplied by the mechanicalshear dissipation from the rotating screws inside the extruder as wellas from the outside heaters that are typically electrical in nature. Theextrudate exiting the extruder is a hot viscous mass or melt that can beshaped to a desired form depending on the shape of the die (cylindricaldie yields a strand or slit die yields a film) that can be sized todesired lengths or passed on to a chill roll unit and pressed againstthe rollers to form thin sheet that will generally flake into smallerpieces.

The extrudate is then subjected to further processing by auxiliarydownstream devices, typically a size reduction step to form particles ofrequired size. Free flowing particles are used for compression, capsulefilling and/or molding into tablets. Fine particles with narrow sizedistribution are generally required for oral suspensions. There arelimitations on the materials that can be used as carriers; as suchmaterials should be amenable to size reduction since low melting solidscannot be milled effectively and efficiently. The limitation inselection of material that can be size reduced may be a factor inrestricting the enhancement in solubility, bioavailability,tastemasking, or sustained release of the pharmaceutical composition.

Spray congealing and spray drying are also known methods for producingfine particles. Spray congealing is carried out by spraying a viscousmelt to generate droplets in a cooling chamber. Spray drying is carriedout with a fluid material containing solvents that is injected into aheated chamber where the generated droplets are dried to form finepowders. Both processes require large foot-prints for limited capacitiesof production. Spray congealing is a dedicated facility for limited typeof fluid material and offers limited flexibility for variedpharmaceutical preparations. Spray drying involves use of a large amountof solvents that may not meet environmental concerns and does not offerscalability from laboratory equipment to commercial equipment. All batchtype processes create variability from lot to lot.

Conventional HME process further requires a multiple equipment setup,under controlled environmental conditions to process pharmaceuticalcompositions. The process also tends to compromise on one or moredesired properties of the pharmaceutical composition.

U.S. Pat. No. 6,318,650 to Breitenbach describes a process for thecontinuous production of solid, particulate preparations of bioactivesubstances, in which the bioactive substances are homogeneouslydispersed in a matrix of thermoplastic auxiliaries, in a screw extruderhaving an extruder barrel. The extruder is divided into a plurality ofzones, so that the process comprises firstly melting the matrixauxiliaries and mixing the bioactive components with the matrixauxiliaries in a heatable zone of the extruder to form a mixture, andsubsequently cooling, precomminuting and finally grinding the mixture ina cooling zone of the extruder to form a powder. It is crucial forsuccess of the process that pure conveying elements are employed in thefirst part of the cooling zone, in order to minimize the energy inputand reduce the shear stress and to maximize the rate of cooling of themelt below the softening point. The process further requires that thematrix polymers are preferably soluble in water but are at leastswellable in water. Accordingly, this process is not suitable for allexcipients such as fatty acids, glyceryl behenate and waxes; andparticularly stearic acid that form a waxy lump on cooling that is notamenable for comminuting inside the extruder. The pure conveying zoneresulting in rapid cooling prior to comminuting also produces somepowders with exposed active medicament.

It is therefore desirable to have an improved process for themanufacture of pharmaceutical compositions in the form of particles thatcan enable improved drug delivery systems, using all excipients andparticularly excipients such as fatty acids like stearic acid, glycerylbehenate and waxes that are not amenable to milling.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: illustrates the intake zone, the melt zone and the fragmentingzone of the extruder in accordance with an embodiment of the invention.

FIG. 2: illustrates a solid input and a cooled solid output from theextruder with an in between continuous semi-solid/viscous phase inaccordance with an embodiment of the invention.

FIG. 3: is a schematic illustration of the disclosed process where amixture of API(s) and the excipient(s) is fed into the intake zone ofthe extruder in accordance with an embodiment of the invention.

FIG. 4: illustrates the use of milling or fragmenting elements withsmall clearances generally resulted in finer fragments withsignificantly reduced or no residue or film development in accordancewith an embodiment of the invention.

FIG. 5: illustrates a F1 type screw configuration in accordance with anembodiment of the invention.

FIG. 6 illustrates a F2 type screw configuration in accordance with anembodiment of the invention.

FIG. 7: shows the particle size analysis report for pharmaceuticalcomposition prepared according to trial 12 in accordance with an,embodiment of the invention.

SUMMARY

A co-rotating twin screw extruder for forming fragments is disclosed.The extruder comprises of an intake zone for receiving one or moreexcipient(s) suitable for oral dosage or one or more excipient(s)suitable for oral dosage along with one or more active pharmaceuticalingredient, a melt zone for softening at least one excipient to form aviscous mass or melt and a fragmenting zone for simultaneous fragmentingand cooling the viscous mass into cooled fragments and an extruderoutlet for recovering the cooled fragments from the extruder.

A method of forming fragments within a co-rotating twin screw extruderis disclosed. The method comprises of feeding one or more excipient(s)suitable for oral dosage into the extruder, softening or melting atleast one excipient to form a viscous mass or melt, and simultaneouslyfragmenting and cooling the viscous mass or melt to obtain cooledfragments, and collecting the cooled fragments from the extruder.

DETAILED DESCRIPTION

A co-rotating twin screw extruder for forming fragments is disclosed.The extruder comprises of an intake zone for receiving one or moreexcipient(s) suitable for oral dosage or one or more excipient(s)suitable for oral dosage along with one or more active pharmaceuticalingredient, a melt zone for softening at least one excipient to form aviscous mass or melt and a fragmenting zone for simultaneous fragmentingand cooling the viscous mass into cooled fragments and an extruderoutlet for recovering the cooled fragments from the extruder.

A method of forming fragments within a co-rotating twin screw extruderis disclosed. The method comprises of feeding one or more excipient(s)suitable for oral dosage into the extruder, softening or melting atleast one excipient to form a viscous mass or melt, and simultaneouslyfragmenting and cooling the viscous mass or melt to obtain cooledfragments, and collecting the cooled fragments from the extruder.

The present disclosure describes a process for the manufacture of apharmaceutical composition using an extruder. The pharmaceuticalcomposition comprises of an active pharmaceutical ingredient (API)component and an excipient component. The process involves feeding theactive pharmaceutical ingredient (API) component along with theexcipient component into an intake zone of the extruder, forming a meltor viscous mass in the melt zone of the extruder and simultaneousfragmenting and cooling the viscous mass or melt in the fragmenting zoneof the same extruder. The extrudate obtained is in the form of cooledsolid fragments comprising of both the API component and the excipientcomponent. FIG. 1 illustrates the intake zone, the melt zone and thefragmenting zone of the extruder.

The extruder is a fully wiping co-rotating twin-screw extruder. Suitableheating and cooling systems are provided on the extruder barrels to heator cool the barrels as desired. Any suitable cooling means known tothose skilled in the art may be used; for example, a fluid coolingjacket surrounding the barrel, liquid nitrogen, dry ice or the like.

The excipient component includes one or more excipients that serve as acarrier, a filler or a binder for the API component. The excipientscould be any pharmaceutical grade material in its solid, semisolid orliquid form. The excipients may be crystalline, amorphous orsemicrystalline in nature. Excipients may be hydrophilic, amphiphilic orlipophilic. Excipients may be ionic or non ionic. Excipients may becelluloses such as ethyl cellulose, hydroxypropylcellulose,hydroxypropyl methyl cellulose. Excipient may also be polyethyleneglycol, polyethylene oxide, polyvinyl pyrrolidone, copovidone, polyvinylacetate or poly methacrylates. Excipients may include plasticizersand/or processing aids such as triethyl citrate, triacetin, propyleneglycol, dibutyl sebacate, diethyl phthalate, glycerol monostearate. Inparticular, excipients may also be fatty acids such as stearic acid,glyceryl behenate and waxes. The excipients may also be additives likedrug-release modifiers, disintegrants and super disintegrants,thickening agents, bulking agents, binders, flow aids, sweeteners, andanti-oxidants. The choice of excipients may be determined by the personskilled in the art based on properties of the API, desired properties ofthe pharmaceutical composition and amenable for fragmentation. Theformation of the melt or viscous mass involves heating the mixture ofthe API component and excipient component above the softening or glasstransition temperature T_(g) or the melting point of the excipient(s).

The temperature and the screw configuration in the melt zone may be suchthat only the excipient(s) or both the excipient(s) as well as the APIsoften or melt to form the viscous mass or melt. The excipient(s) ordrug(s) used could be either crystalline having sharp melting point oramorphous form with a Tg or softening temperature or semicrystallinewith a broad melting point and Tg. Depending on the application andextrusion temperature, the excipient(s) or both excipient(s) and APIcould be taken into the form of a continuous viscous mass or melt withinthe extruder followed by fragmentation while cooling within theextruder. The applications include formation of pharmaceutical particlesthat have one or more of the desired properties not limited tobio-availability enhancement, controlled release, and taste-masking as aresult of one or more of the following actions—disrupting the crystallattice, wetting, encapsulation, complexation, dispersion, formation ofsolid solution or suspensions, etc. Unlike the conventional hot-meltextrusion where a hot viscous mass is extruded out which is then cooledand particle size reduced post extrusion, in the current hot meltfragmentation process the cooling of the viscous mass or melt is donewithin the extruder to a temperature at or below the softeningtemperature or T_(g) or melting point of the excipient(s) to initiatesimultaneous solidification and fragmentation of the viscous mass ormelt. This gives cooled solid fragments that are directly obtained fromthe extruder. The solidified mass is scraped off the extruder surfacesby the extruder elements in the fragmenting zone and fragmented. Thecooling and simultaneous fragmentation of the viscous mass or melt at atemperature ranging from Tg or melting point to below the T_(g) ormelting point enables production of increasingly smaller fragments. Itis preferred that the cooling be continued to sufficiently below theT_(g) or melting point of the carrier so as to promote thesolidification process, enable further milling and fragmentation andachieve the required particle size distribution. The process asdisclosed is therefore a solid input and a cooled solid output from theextruder with an in between continuous semi-solid/viscous phase, asillustrated in FIG. 2. FIG. 3 is a schematic illustration of thedisclosed process where a mixture of API(s) and the excipient(s) is fedinto the intake zone of the extruder. In the simplest process, a mixtureis typically a solid mixture of powders or granules. This mixture isconverted into a melt or viscous mass in the melt zone of the extruder.The viscous mass or melt is then fragmented while cooling in thefragmentation zone to obtain cooled solid fragments of well-mixed APIcomponent and excipient component.

In accordance with an embodiment, the temperature of the melt in thefragmentation zone should be kept below the softening temperature orT_(g) or the melting point of the excipient. Lesser cooling in thefragmentation zone results in larger fragments. Greater cooling in thefragmentation zone forms finer fragments. In accordance with anembodiment, a cooling gradient of the melt towards the exit of theextruder may be maintained.

Formation of residue or film on any surface of the extruder in thefragmenting zone may be minimized by the use of suitable extruderelements. The extruder elements used in the fragmenting zone arepreferably completely wiping. It is also preferred that such elementshave low screw-barrel and screw-screw clearances below 250 microns. Inaccordance with a preferred embodiment, mixing elements are used in thefragmentation zone. WO 2013/128463 describes a mixing element fordistributive mixing having a continuous flight helically formed thereonwith a lead ‘L’, wherein either the flight transforms at least once froman integer lobe flight into a non-integer lobe flight in a fraction ofthe lead ‘L’ and transforms back to an integer lobe flight in a fractionof the lead ‘L’ or the flight transforms at least once from anon-integer lobe flight into an integer lobe flight in a fraction of thelead ‘L’ and transforms back to a non-integer lobe flight in a fractionof the lead ‘L’.

The use of at least one mixing element, along with simultaneous coolingpermits the process to be applied to all excipients, including fattyacids, glyceryl behenate and waxes; and particularly stearic acid.

In accordance with an embodiment, the mixing elements are used in thebeginning of the fragmenting zone, accompanied by simultaneous cooling.The mixing elements are found to be most suitable for initiating thesimultaneous cooling and fragmenting step.

Use of conventional conveying elements with large clearances in thefragmenting zone was found to form large fragments. In some cases,residue build up was also observed within the extruder. As illustratedin FIG. 4, the use of milling or fragmenting elements with smallclearances generally resulted in finer fragments with significantlyreduced or no residue or film development. Examples of fragmentingelements include various blocks of two more segments at 30, 45 or 90degree angles to each other in Forward or Reverse Helix. RKBs are fivesegment blocks at 45 degree stagger angle. NKBs are five segment blocksat 90 degree stagger angle. The Do/Di (ratio of the outer and innerdiameter) of the extruder controls the width of the tip and has animpact on the required particle size distribution as well as preventingresidue build up. A large Do/Di can produce finer fragments (asevidenced by experiments).

In accordance with an embodiment, conveying elements are providedtowards the end of the fragmenting zone. This assists in conveying thecooled and fragmented particles to the outlet of the extruder.

In accordance with an aspect, the present process allows obtainingpharmaceutical composition having controlled particle size in accordancewith the desired application. Depending on the desired drug dosage form,fragments of various size ranges may be obtained. For example—finefragments for forming oral suspensions, medium to coarse fragments forforming tablets or filling into capsules may be obtained. The presentprocess allows obtaining fragments having discrete particle sizedistribution i.e. the particle size distribution may be represented byhistograms. This has particular advantages during compaction offragments to form tablet, where smaller fragments can occupy the voidsformed between the larger fragments.

The present invention has been illustrated in further detail below byway of examples using Cefuroxime axetil and Ketoprofen as API's withvarious excipients.

EXAMPLES

A series of trials were conducted using Cefuroxime axetil and Ketoprofenas API with different excipients under varying process conditions suchas—screw configuration, barrel temperatures to determine the effectthereof on the particle size distribution of the pharmaceuticalcomposition prepared in accordance with the present invention.Experiments were also conducted using only the excipient component tostudy the effect of various polymers on the particle size distributionunder the varying process conditions.

Excipients:

The trials were performed using various excipients in varying ratio andcombinations. The excipients used in the trials are:

1. Stearic acid

2. Polyethylene oxide (PEO)

3. Kollidon® SR (Polyvinyl acetate and Povidone)

4. Calcium carbonate

5. Klucel™ JF (Hydroxypropyl cellulose)

6. Ethocel™ N7 (Ethyl cellulose)

7. Talc

Screw Configuration:

The trials were performed using the twin screw extruder Omega 20manufactured by the assignee herein with two different screwconfigurations F1 and F2, each with a Do/Di of 1.71. Both the F1 and F2screw configurations are provided below in Table 1 and have beenillustrated in FIGS. 5 and 6 respectively. FIGS. 5 and 6 illustrate asingle shaft though the extruder configuration has a pair of shafts withcomplimentary elements. The F2 screw configuration differs from F1 inthat the F2 has different neutral kneading block configuration whichresults in better fragmentation as compared to F1. Both configurationsuse a mixing element in the fragmenting zone. The mixing elements (DSE)as described in WO 2013/128463 are positioned at the beginning of thefragmenting zone (barrel C4). The cooling also begins with barrel C4.

TABLE 1 F1 Screw type F2 Screw type Features Configuration ConfigurationElement length 800 mm 800 mm Max. Screw Speed 1200 rpm 1200 rpm Diameter19.6 mm 19.6 mm Percentage of kneading 21.82 19.95 blocks Screw ElementsElement Number F1-Screw Element type F2-Screw Element type 1 RSE 15/15-1CHS RSE 15/15-1 CHS 2 RFV 45/45 RFV 45/45 3 RFV 45/45 RFV 45/45 4 RFV45/45 RFV 45/45 5 RFN 45/22.5 RFN 45/22.5 6 RSE 30/30 RSE 30/30 7 RSE20/20 RSE 20/20 8 RSE 20/20 RSE 20/20 9 RSE 20/20 RSE 20/20 10 RSE 20/20RSE 20/20 11 RKB 45/5/20 RKB 45/5/20 12 RKB 45/5/20 RKB 45/5/20 13 LSE20/10 LSE 20/10 14 RSE20/20 RSE20/20 15 RSE 20/20 RSE 20/20 16 DSE 20/40A2-A DSE 20/40 17 DSE 20/40 A2-A DSE 20/40 18 DSE 20/40 A2-A DSE 20/4019 RKB 45/5/15 RKB 45/5/15 20 RSE 20/20 RSE 20/20 21 RKB 45/5/15 RKB45/5/15 22 RSE 20/20 RSE 20/20 23 RKB 45/5/15 NKB 90/5/15 24 RSE 20/20RSE 20/20 25 RKB 45/5/15 NKB 90/5/15 26 RSE 20/20 RSE 20/20 27 RKB45/5/15 NKB 90/5/15 28 RSE 20/20 RSE 20/20 29 RKB 45/5/15 NKB 90/5/15 30RSE 20/20 RSE 20/20 31 RKB 45/5/15 NKB 90/5/15 32 RSE 20/20 RSE 20/20 33NKB 90/5/15 NKB 90/5/15 34 RSE 20/20 RSE 30/15 35 NKB 90/5/15 RSE 20/2036 RSE 15/15 RSE 15/15 List of Abbreviations for Elements RSE—RightHanded Screw Element RFV—Right Handed Shovel Element RFN—Right HandedTransition Element LSE—Left Handed Screw Element DSE—Dynamic StirringElement RKB—45 degree stagger angle Right Handed Kneading Block NKB—90degree stagger angle (Neutral) Kneading BlockBarrel Temperatures

The melting point of Ketoprofen is known to be about 90° C. Thetemperature of the melting zone in the barrel is maintained at 60° C. intrial 13 (i.e. below the melting point of API). Cefuroxime axetil is anamorphous drug with a Tg of above 70° C.

Table 2 illustrates the various trials performed using the two drugsalong with different excipients to obtain pharmaceutical composition inaccordance with the present invention as well the trials conducted usingexcipients only. The API and/or the excipient (s), in the ratio providedin the table are blended and fed to the extruder. The barreltemperatures, screw configuration employed in each of the trials arealso indicated in Table 2.

TABLE 2 Particle Surface Volume API size Weighted Weighted Trial and/orScrew Barrel distribution Mean (SWM) Mean (VWM) No. Excipient(s)configuration temperatures (μ) (μ) (μ) 1 Stearic acid + F1 RT, 60, 60,d10-127 222 679 Cefuroxime 60, d50-617 axetil (1:1) 10, 10, 10, 10, 10d90-1322 2 Stearic acid + F1 RT, 60, 60, d10-109 229 617 Cefuroxime 60,d50-550 axetil (1:3.4) 10, 10, 10, 10, 10 d90-1216 3 Stearic acid + F1RT, 60, 60, d10-86 193 525 Cefuroxime axetil 60, d50-446 (1:3.4) + 5%PEO 10, 10, 10, 10, 10 d90-1070 4 Stearic acid + F1 RT, 60, 60, d10-94210 561 Cefuroxime axetil 60, d50-474 (1:3.4) + 10% PEO 10, 10, 10, 10,10 d90-1161 5 Kollidon SR F1 RT, 80, 80, Mean particle diameter- 80,larger than 1 mm 10, 10, 10, 10, 10 6 Kollidon SR + F1 RT, 60, 60,d10-524 772 1013  Stearic acid 60, d50-985 (1:1) 10, 10, 10, 10, 10d90-1569 7 Kollidon SR F1 RT, 80, 80, Mean particle diameter- (70%) +30% 80, larger than 1 mm Calcium carbonate 10, 10, 10, 10, 10 8 KlucelJF F1 RT, 140, 140, Mean particle diameter- 140, larger than 1 mm 10,10, 10, 10, 10 9 Klucel JF + F1 RT, 80, 80, Mean particle diameter-Stearic acid 80, larger than 1 mm (1:1) 10, 10, 10, 10, 10 10 KlucelJF + F1 RT, 80, 80, Mean particle diameter- Stearic acid 80, larger than1 mm (1:1) + 5% talc 10, 10, 10, 10, 10 11 Ethocel N7 + F1 RT, 80, 80,Mean particle diameter- stearic acid 80, larger than 1 mm (1:1) 10, 10,10, 10, 10 12 Stearic acid + F2 RT, 60, 60, d10-40  98 379 Cefuroxime60, d50-322 axetil (1:3.4) 10, 10, 10, 10, 10 d90-781 13 Stearic acid +F2 RT, 60, 60, d10-81 179 549 Ketoprofen 60, d50-448 (1:3.4) 10, 10, 10,10, 10 d90-1175 14 Stearic acid F2 RT, 60, 60, d10-47 115 374 60,d50-316 10, 10, 10, 10, 10 d90-773 15 Kollidon SR F2 RT, 60, 60, Meanparticle diameter- 60, larger than 1 mm 10, 10, 10, 10, 10 16 KollidonSR + F2 RT, 60, 60, d10-273 471 844 Stearic acid 60, d50-809 (1:1) 10,10, 10, 10, 10 d90-1456 17 Klucel JF + F2 RT, 80, 80, d10-401 649 895Stearic acid 80, d50-848 (1:1) 10, 10, 10, 10, 10 d90-1474 18 EthocelN7 + F2 RT, 80, 80, d10-507 776 993 stearic acid 80, d50-959 (1:1) 10,10, 10, 10, 10 d90-1550 (RT = Room Temperature) For trials 5, 7, 8, 9,10, 11 and 15 the mean particle diameter was larger than 1 mm.Particle Size Distribution:

The particle size distribution of each of the composition prepared inaccordance with trials listed in Table 2 was determined using a MalvernMasterSizer 2000. The mean particle diameter of the fragments obtainedin each of the trial has also been listed in Table 2.

FIG. 8 shows the particle size analysis report for pharmaceuticalcomposition prepared according to trial 12. As illustrated in thefigure, the D(0.1), D(0.5), and D(0.9) values for the pharmaceuticalcomposition are 40, 322 and 781 microns respectively. The surfaceweighted mean and volume weighted mean of the fragments was found to be98 and 379 microns respectively.

As illustrated in table 2, comparable mean particle diameter is obtainedin trials 1-4. Comparing trials 1 and 2, the effect of different drugloading on particle size distribution is observed. Comparing trials 2and 12, the effect of screw configuration on particle size distributionis observed. Comparing trials 12 and 13, the effect of different drugson particle size distribution is observed.

Trials Using Excipients Only:

Trials 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18 were conducted usingexcipients only, alone and in combination with other excipients.

Comparing trials 14 and 15, the effect of different excipients onparticle size distribution is observed. Stearic acid being crystallineis more brittle than Kollidon SR that is amorphous and accordinglysmaller particle size was obtained with stearic acid. The result oftrial 14 also indicate that stearic acid, a difficult to mill excipientusing conventional techniques, can also be used for pharmaceuticalcompositions using the hot melt fragmentation process described herein.Trials 16 through 18 illustrate the effect of a combination ofexcipients on the particle size distribution. Trials 16 through 18 alsoindicate that difficult to mill excipients can also be used for hot meltfragmentation in combination with other excipients. Similar results wereobserved in trials 5 and 6 using a different screw configuration.

Comparing trials 6 and 16, the effect of different screw configurationson the particle size distribution is observed. Fragments obtained usingthe screw configuration F2 were finer than using the screw configurationF1. Similar results were observed in trials 2 and 12; trials 11 and 18;and trials 9 and 17. It is believed that this is a direct result of thebetter fragmentation properties exhibited by F2 type screwconfiguration.

The above data suggests that altering the excipients, process parameterssuch as temperatures, screw configuration can be used to preparefragments of desired size ranges.

Specific Embodiments are Described Below

A co-rotating twin screw extruder for forming fragments comprising anintake zone for receiving one or more excipient(s) suitable for oraldosage or one or more excipient(s) suitable for oral dosage along withone or more active pharmaceutical ingredient, a melt zone for softeningat least one excipient to form a viscous mass or melt and a fragmentingzone for simultaneous fragmenting and cooling the viscous mass intocooled fragments and an extruder outlet for recovering the cooledfragments from the extruder.

Such extruder(s), wherein the fragmenting zone comprises of milling,mixing or fragmenting elements.

Such extruder(s), wherein the fragmenting zone comprises of at least onemixing element having a continuous flight helically formed thereon witha lead ‘L’, wherein either the flight transforms at least once from aninteger lobe flight into a non-integer lobe flight in a fraction of thelead ‘L’ and transforms back to an integer lobe flight in a fraction ofthe lead ‘L’ or the flight transforms at least once from a non-integerlobe flight into an integer lobe flight in a fraction of the lead andtransforms back to a non-integer lobe flight in a fraction of the lead‘L’.

Such extruder(s), wherein the fragmenting zone comprises of at least onemixing element and the mixing element is positioned at the beginning ofthe fragmenting zone.

Such extruder(s), wherein the excipient(s) is selected from the groupconsisting of a fatty acid, glyceryl behenate and waxes.

Such extruder(s), wherein the fatty acid is stearic acid.

Such extruder(s), wherein the temperature of the melt zone is above thesoftening temperature or glass transition temperature Tg or meltingpoint of at least one excipient to enable formation of the viscous massor melt.

Such extruder(s), wherein the fragmenting zone is provided with acooling system and the temperature of the fragmenting zone is at orbelow the softening temperature or glass transition temperature Tg ormelting point of at least one excipient for cooling the viscous mass ormelt.

Such extruder(s), wherein the cooling is uniform throughout thefragmenting zone.

Such extruder(s), wherein the fragmenting zone has an increasing coolinggradient towards the extruder outlet.

Further Specific Embodiments are Described Below

A method of forming fragments within a co-rotating twin screw extrudercomprising:

-   -   a. feeding one or more excipient(s) suitable for oral dosage        into the extruder;    -   b. softening or melting at least one excipient to form a viscous        mass or melt; and    -   c. simultaneously fragmenting and cooling the viscous mass or        melt to obtain cooled fragments;    -   d. collecting the cooled fragments from the extruder.

Such method(s), comprising feeding one or more excipient(s) suitable fororal dosage along with one or more active pharmaceutical ingredient intothe extruder.

Such method(s), wherein the excipient(s) is selected from the groupconsisting of a fatty acid, glyceryl behenate and waxes.

Such method(s), wherein the fatty acid is stearic acid.

Such method(s), wherein the simultaneous fragmenting and cooling isachieved by milling, mixing or fragmenting elements.

Such method(s), wherein the simultaneous fragmenting and cooling isachieved by at least one mixing element having a continuous flighthelically formed thereon with a lead ‘L’, wherein either the flighttransforms at least once from an integer lobe flight into a non-integerlobe flight in a fraction of the lead ‘L’ and transforms back to aninteger lobe flight in a fraction of the lead or the flight transformsat least once from a non-integer lobe flight into an integer lobe flightin a fraction of the lead ‘L’ and transforms back to a non-integer lobeflight in a fraction of the lead ‘L’.

Such method(s), wherein the mixing element is positioned at thebeginning of the fragmenting zone.

INDUSTRIAL APPLICABILITY

The disclosed process for the manufacture of pharmaceutical compositionsusing an extruder finds application in size controlled manufacturing ofvarious drug dosage forms. Fragments may be obtained for tabletcompression, capsule filling and for preparing sprinkles or suspensionsfor oral administration without involving complex downstream auxiliaryequipments. The pharmaceutical composition obtained using the disclosedprocess may result in improved characteristics such as enhancement ofthe dissolution rate and/or bio-availability of the drug, controlledrelease of the drug, taste masking, stability enhancement etc. Thepresent process also prevents contamination and reduces any yield lossof the pharmaceutical composition, encountered in multi-equipmentprocesses viz. conventional Granulation/compaction processes orconventional Hot Melt Extrusion process.

The disclosed process is suitable for all excipients, especiallydifficult to mill excipients such as stearic acid. The simultaneouscooling and fragmenting using fragmenting or mixing elements in thefragmentation zone aids in obtaining the desired fragments.

The extruder as disclosed is suitable for forming pharmaceuticalfragments using all excipients, particularly difficult to millexcipients such as stearic acid.

We claim:
 1. A co-rotating twin screw extruder for forming fragmentscomprising an intake zone for receiving one or more excipient(s)suitable for oral dosage or one or more excipient(s) suitable for oraldosage along with one or more active pharmaceutical ingredient(s), amelt zone for softening at least one excipient to form a viscous mass ormelt, a fragmenting zone and an extruder outlet, the fragmenting zonecomprising at least one element having a continuous flight helicallyformed thereon with a lead ‘L’, wherein either the flight transforms atleast once from an integer lobe flight into a non-integer lobe flight ina fraction of the lead ‘L’ and transforms back to an integer lobe flightin a fraction of the lead ‘L’ or the flight transforms at least oncefrom a non-integer lobe flight into an integer lobe flight in a fractionof the lead ‘L’ and transforms back to a non-integer lobe flight in afraction of the lead ‘L’, for simultaneous fragmenting and cooling theviscous mass into cooled fragments, and wherein the cooled fragments arerecovered from the extruder outlet of the extruder.
 2. A co-rotatingtwin screw extruder as claimed in claim 1, wherein the fragmenting zonecomprises of milling, mixing or fragmenting elements.
 3. A co-rotatingtwin screw extruder as claimed in claim 1, wherein the mixing element ispositioned at a beginning of the fragmenting zone.
 4. A co-rotating twinscrew extruder as claimed in claim 1, wherein the excipient(s) isselected from the group consisting of a fatty acid, glyceryl behenateand waxes.
 5. A co-rotating twin screw extruder as claimed in claim 4,wherein the fatty acid is stearic acid.
 6. A co-rotating twin screwextruder as claimed in claim 1 wherein the temperature of the melt zoneis above the softening temperature or glass transition temperature Tg ormelting point of at least one excipient to enable formation of theviscous mass or melt.
 7. A co-rotating twin screw extruder as claimed inclaim 1 wherein the fragmenting zone is provided with a cooling systemand the temperature of the fragmenting zone is at or below the softeningtemperature or glass transition temperature Tg or melting point of atleast one excipient for cooling the viscous mass or melt.
 8. Aco-rotating twin screw extruder as claimed in claim 1 wherein thecooling is uniform throughout the fragmenting zone.
 9. A co-rotatingtwin screw extruder as claimed in claim 1 wherein the fragmenting zonehas an increasing cooling gradient towards the extruder outlet.
 10. Amethod of forming fragments within a co-rotating twin screw extrudercomprising: a. feeding one or more excipient(s) suitable for oral dosageinto the extruder; b. softening or melting at least one excipient toform a viscous mass or melt; c. simultaneously fragmenting and coolingthe viscous mass or melt by using, at least one mixing element having acontinuous flight helically formed thereon with a lead ‘L’, whereineither the flight transforms at least once from an integer lobe flightinto a non-integer lobe flight in a fraction of the lead ‘L’ andtransforms back to an integer lobe flight in a fraction of the lead ‘L’or the flight transforms at least once from a non-integer lobe flightinto an integer lobe flight in a fraction of the lead ‘L’ and transformsback to a non-integer lobe flight in a fraction of the lead ‘L’ in thefragmenting zone to obtain cooled fragments within the extruder; and d.collecting the cooled fragments from the extruder.
 11. A method asclaimed in claim 10 comprising feeding one or more excipient(s) suitablefor oral dosage along with one or more active pharmaceutical ingredientinto the extruder.
 12. A method as claimed in claim 10 wherein theexcipient(s) is selected from the group consisting of a fatty acid,glyceryl behenate and waxes.
 13. A method as claimed in claim 12 whereinthe fatty acid is stearic acid.
 14. A method as claimed in claim 10wherein the simultaneous fragmenting and cooling is achieved by milling,mixing or fragmenting elements.
 15. A method as claimed in claim 10wherein the mixing element is positioned at the beginning of thefragmenting zone.